What PAG AC Compressor Oil?

[Sunroof]

I just finished cleaning out my AC system on my 1973.5T. It took three cans of that pressurized "System Flush" cleaner, a lot of compressed air with good success. The amount of dirty oil and sludge probably from the evaporator and condensers alone was amazing, but after the third flush it was all clean! Great stuff.

Now, I am ready to recharge, but need to add oil to my Sanden compressor. The question is, do I add oil to the compressor only and use non-oil coolant, or use both with a limited amount of oil in the compressor?

I noted that PAG oil comes in varying number designations, which I am not sure what they represent (viscosity?, heat tolerance? lubrication property?). If anyone knows just how much oil should be added to the compressor or the entire system (front and rear condensers, Behr evaporator, new barrier lines and new drier), and the specific number, please advise.

Thanks

Bob
73.5T